linux-kernel - Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time

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Message-ID: <20151009104712.GD2166@localhost>
Date:	Fri, 9 Oct 2015 12:47:12 +0200
From:	Miroslav Lichvar <mlichvar@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
	y2038@...ts.linaro.org, John Stultz <john.stultz@...aro.org>,
	Prarit Bhargava <prarit@...hat.com>,
	Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t
 overflow

On Fri, Oct 09, 2015 at 12:38:32PM +0200, Thomas Gleixner wrote:
> On Fri, 9 Oct 2015, Miroslav Lichvar wrote:
> > Do you feel the same about preventing the time from reaching
> > KTIME_MAX?
> 
> That's going to happen in ~500 years from now.

At any time if you include accidents and attacks on services with
the CAP_SYS_TIME capability (e.g. NTP/PTP implementations). Even with
32-bit time_t you are not safe, the time can be set forward by any
amount with multiple adjtimex(ADJ_SETOFFSET) calls.

-- 
Miroslav Lichvar
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